Recently, the interrelation between cancer and an increase of amounts of polyamines in body fluids such as blood, urine and lymph has attracted attention, and the use of a polyamine oxidase as an enzyme for diagnosis of cancers has been developed (see Japanese Patent Application Laid-Open Specification No. 9492/75).
Polyamine oxidases derived from animal and plant tissues as supply sources have heretofore been used. However, each of the polyamine oxidases derived from animal and plant tissues is poor in activity, and it is difficult to obtain them in large quantities. Furthermore, it is very difficult to produce these polyamine oxidases at low costs on an industrial scale.